Transcript of Causal - Comparative Research

by Büşra Demir & Delal K. DemirWhat is Causal - Comparative Research?Investigators attempt to determine the cause or consequences of differences that ALREADY exist between or among groups of individuals.the reason for

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the results of a differenceThe difference has already been occurred.Causal - comparative research is also referred to sometimes as "ex post facto" (from the Latin for "after the fact") research.Much of the research in medicine and sociology is causal - comparative in nature. (because of the ethical reasons)Types of Causal - Comparative ResearchType 1: Exploration of effects (dependent variable) caused by membership in a given groupQuestion: What differences in abilities are caused by gender?Research hypothesis: Females have a greater amount linguistic ability than males.Type 2: Exploration of causes (independent variable) of group membershipQuestion: What causes individuals to join a gang?Research hypothesis: Individuals who are members of gangs have more aggressive personalities than individuals who are not members of gangs.Type 3: Exploration of the consequences (dependent variable) of an interventionQuestion: How do students taught by the inquiry method react to propaganda?Research hypothesis: Students who were taught by the inquiry method are more critical of propaganda than others.Causal - Comparative ResearchExample:A researcher is interested in the reason(s) why some individuals become addicted to alcohol while others develop a dependence on pills.Problem Formulationidentify and define the particular phenomena of interestconsider / speculate possible causes for, or consequences of, these phenomenaincorporate the possible causes into a more precise statementSampledefine carefully the characteristics to be studied and then select groups that differ in this characteristicsform reasonably homogenous groupsmatch the defined groups on one or more variablesInstrumentationno limits on the types of instruments that may be used: - achievement tests,- questionnaires,- interview schedules,- attitudinal measures,- observational devices,- etc.DesignSubject CharacteristicsMatching of SubjectsFinding or CreatingHomogenous GroupsStatistical MatchingOther ThreatsEvaluating Threats to Internal Validity in Causal-Comparative StudiesStep 1: What specific factors either are known to affect or may logically be expected to affect the variable on which groups are being compared? Step 2: What is the likelihood of the comparison groups differing on each of these factors?Step 3: Evaluate the threats on the basis of how likely they are to have an effect, and plan to control for them.Possible causes of student dropping out in inner-city high schools.Hypotheses: 1. Family Instability2. Low Student Self-esteem3. Lack of a support systemSubject Characteristics:1. Socioeconomic level of the family2. Gender3. Ethnicity4. Marketable job skillsMortalityLocationOther ThreatsConstruct frequency polygonsCalculate means and standard deviationsT-test to show differences between meansThe result do not prove cause and effect, but only identifying the relationship